Generalised calculation of NMR imaging edge effects arising from restricted diffusion in porous media

The theoretical problem of how to describe apparent image spin density under conditions of restricted diffusion, given any general gradient sequence, is intrinsically complex. Here we demonstrate a simple approach to calculating the signal and the corresponding density in nuclear magnetic resonance (NMR) imaging experiments by means of an impulse-propagator method based on matrix multiplication. The multiplication scheme bears a natural and straightforward relationship to the k-space sampling, while the matrices themselves are calculated from the eigenmodes of the pore diffusion equation. Good agreement is found between theoretical predictions and the results of micro-imaging experiments on water trapped in rectangular pores whose walls are spaced by 100 microns along the read direction.     

Neutrophils play a critical role in early resistance to amebic liver abscesses in severe combined immunodeficient mice

Animal models of liver abscess formation with Entamoeba histolytica suggest that the neutrophil is the first cell of the host immune system to interact with the invading ameba. In vitro studies have suggested that lysis of neutrophils by virulent amebae may exacerbate the damage seen in amebic liver abscesses. To investigate the role of neutrophils in vivo, we used the severe combined immunodeficient (SCID) mouse model of amebic liver abscess formation and compared liver damage in neutrophil-depleted and control mice. We found that neutrophil-depleted animals have significantly larger amebic liver abscesses at early stages of infection and that abscesses in neutrophil-depleted SCID mice lack the prominent inflammatory cell ring seen in amebic liver abscesses in control SCID mice. These data suggest that neutrophils play a protective role in the early host response to amebic infection of the liver.     

Complementary medicine: a review of immunomodulatory effects of Chinese herbal medicines

Normal aging selectively impairs some forms of learning. For example, aging rabbits require more than twice as many trials to acquire 500-ms trace eyeblink conditioning than do young rabbits. N-methyl-D-aspartate (NMDA) receptor antagonists also impair trace conditioning. The effects of daily D-cycloserine (DCS; a partial agonist of the NMDA receptor-glycine site) treatment were tested on trace conditioning of young or aging rabbits using a conservative quantitative approach. DCS dose dependently improved acquisition, maximally reducing trials to criterion by approximately 50%. Dose-response curves were right-shifted by aging (twice the dose was required to achieve the same enhancement compared with controls). DCS did not affect nonassociative performance but sharpened the conditioned stimulus tone intensity discrimination. DCS thus can functionally modulate NMDA receptors in normal aging, enhance associative learning at all ages, and reduce or reverse age-dependent learning deficits.     

Comparison of inotropic and chronotropic effects of vasoactive intestinal peptide in isolated dog atria

In an in vitro study the effect of various thrombin inhibitors (argatroban, efegatran, DuP 714, recombinant hirudin and PEG-hirudin) on platelet activation in whole blood was investigated. Blood was drawn from normal human volunteers using the double syringe technique without use of a tourniquet to avoid autoaggregation of platelets. Blood was anticoagulated with either argatroban, efegatran, DuP 714, hirudin or PEG-hirudin at final concentrations of 10 micrograms/ml. Blood samples were then incubated at 37 degrees C either with saline, r-tissue factor, arachidonic acid, adenosine diphosphate or collagen. At definite times (1, 2.5, 5, 10 min) aliquots were taken and after various steps of fixative procedure the percentage of platelet activation was measured using fluorescent monoclonal antibodies to platelet surface receptors GPIIIa (CD-61) and P-selectin (CD-62). Flow cytometric analysis showed a platelet activation after all agonists used. All thrombin inhibitors studied caused a nearly complete inhibition of r-tissue factor-mediated platelet activation. In contrast, after activation with the other agonists an increased percent CD-62 expression was found with a maximum after 2.5 to 5 min. The results show that in whole blood thrombin inhibitors are effective in preventing platelet activation induced by r-tissue factor. The formation of active serine proteases including thrombin may be effectively inhibited by these agents. The observations further suggest that while thrombin inhibitors may control serine proteases, these agents do not inhibit the activation of platelets mediated by other agonists.     

Passive immune globulin therapy in the SIV/macaque model: early intervention can alter disease profile

In this study, we investigated the impact of recombinant interleukin-2 (rIL-2) after high dose chemotherapy and autologous bone marrow transplantation (ABMT) in 25 patients with refractory or relapsed Hodgkin's disease (HD) (11 patients) and non Hodgkin's lymphoma (NHL) (14 patients). 48% of patients had resistant disease, 84% achieved complete remission after ABMT. rIL-2 was started at a median of 54 days post-transplant and consisted of a first cycle of 5 days followed by 4 cycles of 2 days every other week. Patients received a mean of 160 x 10(6) IU/m2 rIL-2 and hematological toxicity was moderate and transient. None of the 5 evaluable patients with measurable disease responded to rIL-2. After a 5 year median follow-up, the probability of survival and DFS is 72% (HD: 73% and NHL: 70%, p = NS) and 45% (HD: 36% and NHL: 48%, p = NS) respectively. These somewhat encouraging results warrant further evaluation of rIL-2 after ABMT in controlled studies, especially in NHL patients stratified for previous chemosensitivity.     

Evaluation of Biolog system for identification of some gram-negative bacteria of clinical importance

The Biolog system (Biolog, Inc., Hayward, Calif.) was evaluated for the identification of 55 gram-negative taxa (789 strains) likely to be encountered commonly in clinical laboratories. The Biolog system performed best with oxidase-positive fermenters and biochemically active nonfermenters and had the most problems with unreactive nonfermenters. It gave significantly better results when the MicroPlates were read manually rather than when they were read by the automated reader. Plates read manually gave the following performances: oxidase-positive fermenters, five taxa, 64 strains, 92% correct, 3% not identified, and 5% incorrect; biochemically active nonfermenters, eight taxa, 122 strains, 88% correct, 6% not identified, and 6% incorrect; members of the family Enterobacteriaceae, 35 taxa, 511 strains, 77% correct, 8% not identified, and 15% incorrect; unreactive nonfermenters, seven taxa, 92 strains, 38% correct, 24% not identified, and 38% incorrect. We found the system easy to use, but while for 39 of 55 of the taxa an identification rate of > 70% was achieved, problems were encountered, particularly with identification of capsulated strains of some Enterobacter and Klebsiella taxa, as well as the least biochemically active Moraxella and Neisseria strains.